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published: Jun-24-2018, updated: Jul-11-2021

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NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons flat’ sharp peaks and ‘wiggles’. I do not use smoothing because some info about sound quality is lost when plots are smoothed.

Aside from a small correction of the microphone itself also some correction in the lowest frequencies is applied to the plots to compensate for the perceived loss of bass when using headphones. This is described HERE in more detail.
A ‘horizontal‘ frequency response curve on the shown frequency response plots on this website thus indicates a perceived ‘flat’ tonal signature.

ALL measurements are made with a good SEAL on a flatbed measurement rig.
The shape of your head, bone structure, pad size, pad ‘softness,  (compliance), hair or no hair and or wearing glasses may (drastically) change the frequency response of some headphones, so… your personal experience may differ substantially from these plots.

Frequency response (tonal balance) is the most sound-determining aspect of headphones. A horizontal line shows audible neutral response in the plots on this website. Deviations in different severities at different frequency bands have an effect on the sound character.
The bigger the deviation the stronger the effect.

Below an aid to help determining the sound character of headphones with relation to the frequency response.


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Audeze LCD-MX4


The Audeze LCD-MX4 is an open orthodynamic headphone. It retails for around $ 3000.-
Despite the efforts of using magnesium and carbon this headphone still is quite heavy in weight (550 gr.)  which may still put some people off.
Strangely enough the weight is not specified anywhere just that it is 30% lighter. This would make it around 450gr. but reviewers report it as 550 gram. This is about a 10% reduction in weight.
The headband is made of carbon and pads are soft and made of real leather or micro-suede (your choice).
The cups are made of magnesium and rounded off around the edges.

This headphone is designed to be driven directly from portable sources. Because of this the impedance is quite low (around 20Ω) and the efficiency is quite high (105 dB/mW). Even higher than the HIFIMAN Ananda. As a result just a small voltage is already enough to create a decent SPL.

It is intended for home and studio usage as the open nature of the headphone doesn’t make it suited for commuting. Of course it is transportable in its case and can be listened to on all lcations just from a phone, tablet or laptop.
Given its sound quality it really should be driven from better DAP’s or from decent headphone amplifiers though using custom EQ as well.

It has a 4-pin mini XLR connector on each cup and thus has a cable with a Y-splitter in the middle terminated in a 6.3mm TRS jack. Also included is a small converter cord from 6.3 to 3.5mm TRS. A missed point could be that instead of the 6.3mm TRS a 4.4mm TRRS jack wasn’t used. I guess the audio world isn’t embracing this connector.
The cable is a bit short for desktop duties and too long for ‘portable’ duties with the added 6.3 to 3.5mm conversion cable. What would it cost to include 2 different length cables ?


Type: over ear, open
Usage: home and studio usage
Driver type: orthodynamic
Pads: replaceable, slanted soft real leather pads
Inner pad dimensions: depth: 32mm rear, 25mm front side, H: 65mm, W: 50mm
Collapsible: No.
Headphone connector: 4-pin Mini XLR (marked with colour code ring)
Cable entry: dual sided
Cable: replaceable,  1.6m. 6.3mm TRS jack with 6.3 to 3.5mm adapter cord
Driver size: 80mm diameter, active area 65mm x 50mm
Nom. power rating:  5W (15W peak power)
Nom. voltage:  10 Vrms (17V peak)
Nom. current:  500 mA (0.85A peak)
Max. S.P.L. 140 dB (at 10V)
Impedance: 20 Ω
Efficiency: 105 dB @ 1mW
Sensitivity: 122 dB @ 1V
Weight: 550 g.
Clamping force: low/medium
Accessories: sturdy travel case, 1.6m. cable with 6.3mm TRS jack and 6.3mm to 3.5mm TRS adapter


Below the frequency response of the LCD-MX4 (Left, Right)


Channel matching is excellent as it should be at this price point.
The frequency response shows a neutral-ish tonal response from 10Hz to 1kHz with a small ‘bright’ tilt to it. There is a mild mid-range emphasis.
Bass as well as sub-bas is there and of high quality. This is not basshead type of bass but works well with well made recordings. Older rock and pop records may sound a little too bass shy.
While the mids are quite neutral it does lack ‘clarity/presence’. The dive towards 4kHz is responsible for this. That dip is somewhat smaller in reality than how it measures because the so-called Concha-gain. This will make this measured dip smaller than it looks. It is still there though, just not as deep as the plots suggest.
Treble extension of the LCD MX4 is good but is on a too low level when one is looking for your typical detailed ‘high-end’ sound with clear cymbals.
The ‘peaks’ around 10kHz and 20kHz nearly reach the 90dB line so some of the treble will be audible but overall the level will be on the lower side, which some folks prefer by the way.
These headphones really need some EQ and it looks like Audeze agrees as they supply their own EQ program.


Seal can be an issue with closed-back headphones but is usually less of a problem for open headphones. Breaking the seal (improper fit on the head) usually means a loss of (sub)bass. The LCD-MX4 is not different than most other open headphones in this aspect. Perfect seal, with thin armed glasses and with thick armed glasses.


There is a slight loss of subbass below 20Hz which IMO is not audible. Lowest bass frequencies do not suffer at all and in fact even slightly increase in amplitude.
A perfect seal thus is not essential for these headphones.

The Audeze line-up has quite a few models that differ somewhat in tonal balance and nuances. Below a plot with the open versions in the Audeze line-up.
LCD-2 F, LCD-2 Classic, LCD-3 F, LCD-XLCD-4 and LCD-MX4

tonal balance all LCD open

As can be seen the differences in tonal balance are not very big between all models but definitely are there.

To make the differences a little easier to spot below some comparison plots.
LCD-MX4 versus LCD-4


The LCD-MX4 has a few dB more subbas. It also has a small emphasis around 1kHz and the LCD-4 a little higher at 1.5kHz. Treble levels of the LCD-4 are about 5dB higher. This all makes the LCD-MX4 a bit ‘darker’. Some people were ‘complaining’ that the previous LCD’s were too bright and that those people actually preferred the original LCD-2 which was darker sounding. My personal opinion is that I prefer a brighter sound (probably to do with age and taste).

I have no measurements available of the older LCD-2 but do have the measurements of the LCD-2 Classic which is supposed to be closer to the sound of the original LCD-2.
Below the LCD-2 Classic versus the LCD-MX4.

LCD MX4 vs LCD2 Classic

That’s quite a surprise. These 2 won’t sound that different in overall tonal balance. Above 10kHz there are differences though which indicate the treble response isn’t entirely the same. The LCD-2 Classic has about 5dB more presence around 13kHz but the LCD-MX4 has 5 dB more presence from 13kHz to 20kHz. As the ‘air’ is in the highest frequencies one could conclude that the more expensive LCD-MX4 has more ‘air’.

Below the difference between the LCD-2 Fazor and the LCD-MX4

MX4 vs LCD2-Fazor

The LCD-MX4 doesn’t sound like the LCD-2 Fazor. The LCD-2F has more bass, is closer to ‘neutral’ , doesn’t have the peak at around 1kHz. Also the LCD-2F has more clarity/presence (even though that one is also lacking slightly there) and has a lot more treble as well.

Below the LCD-MX4 versus the LCD-3 (Fazor).

LCD3 vs MX4

The LCD-MX4 doesn’t sound like the LCD3-Fazor either. The LCD-3F also has more bass, is closer to ‘neutral’ and also doesn’t have the peak at around 1kHz. The LCD-3F has about the same level of clarity/presence and sounds about equally ‘laid back’ but is brighter and more ‘airy’ sounding. The LCD-3F is perhaps a bit too emphasized there and becoming too ‘ethereal’.

Below the LCD-MX4 versus the LCD-X

LCD X vs MX4

These two headphones also differ. The LCD-X showing a bit more ‘body’ in the mids and bass and being less ‘laid back’ with a lot more treble up top. Perhaps the LCD-X is closest to ‘neutral’. A matter of taste.

Note that this headphone was measured at ears-unlimited-logo where unavoidable background noises were present in the demo room. Distortion levels and spectrum plot performance may thus be better in reality than shown on the plots.

Below the distortion plots of the LCD-MX4. (only right channel shown)
The distortion products are shown in dB.

Dist MX4 R

The distortion is impressively low and are below the capabilities of my test rig.
The 2nd harmonic distortion is most likely lower than the 0.2% shown in the plots. This is due to the limit of the measurement rig which is reached.

Below the same plot except shown in percentages.

Dist MX4 R percent

No negative remarks here. Exceptionally low distortion

Below the CSD of the LCD-MX4 (Left and Right channel are superimposed)


The driver seems to be pretty well damped and is not showing all kinds of resonances above 4kHz that are seen in Hifiman headphones.

Below the spectrum plot of the LCD-MX4 (Left channel).

spectr MX4 L

This plot too shows no deal breaking issues at all. Bass and mids are quite clean.
The small signals around 1.5kHz may well not be coming from the headphone but are most likely sounds present in the demo room it was measured in.

By lack of oscilloscope shots (not enough time to measure that) below a step response plot of the LCD-MX4. (Left channel)

step L MX4
The initial rise doesn’t reach the 0dB line at all. It remains about 8dB below the mids (the peak around 0.4ms). Bass extension is very good as indicated by the just slightly downwards sloping horizontal trace. The midrange emphasis (the ‘hump’ around 0.4ms) is clearly visible which will make voices and certain instruments stand out yet lack in clarity.


The LCD-MX4 has very low amounts of distortion. Tonal balance is coloured. A bit too ‘forward’ in the mids and lacking in clarity and presence. Forward and ‘laid back’ at the same time. Treble is present and well extended but a bit on the subdued side. I am sure there are buyers that will be very glad with this tonal character.
A cheaper alternative to this headphones, when seeking a similar tonal character, is the LCD-2C with the side note that the LCD-2C is not as efficient and really needs an amplifier to drive it properly.
Those who want a bit more clarity and bass should reach for tone controls / EQ and get a nicely made headphone that reacts well to EQ.
Recommended for indoor usage because of it’s open nature. It can be driven directly from a phone, tablet or DAP. Connecting it to a decent amp may still be somewhat beneficial.
Some people may not like the, still rather high, weight others won’t mind.
Comfort on the head is very good though.
The comfortable leather pads do seal quite good, which some may find unpleasant as it kind of ‘sucks’ to your head when you pull the headphones from your head.

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